The Elusive Gravy Base

I wasn't quite sure where to post this, but I'm looking for one particular gravy base that my grandmother used to use all the time, and was hoping you might have ideas as to what brand and type of gravy base it might be.

Before I go on, here's why I'm posting this on a forum in the first place:

My grandmother was a cook for a living. She first worked in bush camps for construction companies who sent men out to build roads in northern Quebec, she worked for the Canadian Military as a cook on a boat at some point, and finally she bought a motel in Northern Ontario and cooked full time in the adjoining restaurant.

During all her years as cook, she was very good at keeping her recipes secret. When my mother asked her for a recipe, she would always leave an ingredient out so that it wouldn't turn out quite the same. Same goes for this gravy base. She would get it from a Wholesaler through her Sister's store, and when my Mom asked what gravy base she used, she would instead send us some in a Ziploc Bag.

Unfortunately, my Grandmother passed away in a car accident just before Christmas of 2012, and took her recipes with her to the grave. We asked her but she says she cannot remember what brand of gravy base it was.

I don't have a whole lot of information about this gravy base, but here's what I can tell you:
1. My grandfather used to pick it up at his sister-in-law's store and remember's the label being yellow.
2. The gravy base itself is an extremely dark brown, nearing black. (Not like most of the stuff you buy in the grocery store that is typically a light brown)

The only yellow labelled gravy base that we've found is made by "Berthelet", it can only be found through a wholesaler, but When we got it, it still turned out to be a light brown colour.

I don't know if this helps, but my grandmother was a big fan of "Knorr" products.